The present invention relates to femoral neck osteotomy, and more particularly to a guide and method for cutting a femoral neck at an angle of 45.degree. to the long shaft axis of the femur.
By way of explanation and as used throughout, the femur extends from the hip to the knee. At the upper end, the femur articulates with the acetabulum by a rounded head connected with the shaft of the bone by an oblique neck. A pair of eminences called trochanters are located at the junction of the neck and shaft for the attachment of muscle. The great or greater trochanter is situated at the outer part of the upper end of the shaft at its junction with the neck, and the less or lesser trochanter is at the lower back part of the junction of the shaft and neck. Below, the femur articulates with the tibia by a pair of condyles.
Hip arthroplasty procedure includes anesthesia and patient placement on a table in proper orientation. The patient's body is then stabilized, scrubbed, prepared and draped. An incision is made and the subcutaneous tissue is divided. Appropriate soft tissue is excised and/or divided for exposure and dislocation of the hip. After the femoral head is dislocated from its associated acetabulum, the head is rotated for better exposure. The next step is femoral neck osteotomy wherein the head and neck are cut away from the femur shaft.
The depth of the cut and the cutting plane are most critical and the plane should be 45.degree. to the long shaft axis of the femur. Heretofore, a trial hip prosthesis was used as a guide for estimating the location and direction of the cut. Utilizing this procedure, the femoral trial was simply placed over the proximal femur after dislocation and the prosthesis collar used as a reference for scribing a cut line on the femoral neck. This step was followed by actually cutting along the scribed line to remove the femoral head and neck. Often the cut was not located in the proper 45.degree. plane, thereby causing an improper interface between the prosthesis collar and the cut edge of the bone and poor stress distribution between the prosthesis and the femur.